Coding/modulation scheme selection technique

Abstract

In a wireless data network, such as a General Packet Radio Service (GPRS) network, a transmitter uses one of k coding/modulation schemes for transmitting data. The transmitter initially selects a coding/modulation scheme, C, as a function of carrier-to-interference ratio (C/I) measurements. The transmitter then calculates the number of blocks, B, required to transmit a number of data packets, D, using the coding/modulation scheme C. In addition, the transmitter calculates the number of blocks required to transmit the number of data packets, D, for each coding/modulation scheme that is stronger than the selected coding/modulation scheme C. The transmitter finally selects that coding/modulation scheme that results in transmitting the number of data packets D in B blocks using the strongest coding/modulation scheme. As a result, each block is transmitted using the strongest coding/modulation scheme available.

What is claimed:  
     
       1. A method for selecting one of k coding/modulation schemes in a transmitter, the method comprising the steps of: 
       (a) measuring a channel quality metric (CQM);  
       (b) selecting one of the k coding/modulation schemes as a function of the measured CQM;  
       (c) calculating a number of blocks, B, required to transmit a given amount of data, D, using the selected coding/modulation scheme; and  
       (d) selecting the strongest coding/modulation scheme capable of transmitting as packets, the given amount of data packets D in B blocks.  
     
     
       2. The method of claim  1  wherein step (d) includes the step of calculating a respective number of blocks required to transmit the data D for each coding/modulation scheme that offers higher protection than the selected coding/modulation scheme. 
     
     
       3. The method of claim  1  wherein the transmitter is a wireless transmitter. 
     
     
       4. A transmitter comprising: 
       receiving circuitry for use in measuring a channel quality metric (CQM);  
       a processor for selecting one of k coding/modulation schemes for use in transmission of an amount of data, D;  
       wherein the processor (a) selects one of the k coding/modulation schemes as a function of the measured CQM, (b) calculates a number of blocks, B, required to transmit the data, D, using the selected coding/modulation scheme, and (c) selecting the strongest coding/modulation scheme capable of transmitting as packets, the given amount of data packets D in B blocks.  
     
     
       5. The apparatus of claim  4 , wherein the transmitter is a wireless transmitter.